Aging (greater than 1 year) BALB mice are deficient in their humoral antibody response. A T cell defect is indicated since the defect can be overcome by infustion of thymocytes. Polynucleotide adjuvants (poly A:U) also restored antibody formation in aged mice. Accordingly, the objective of the proposed research is to determine whether polynuceotides function by acting on T lymphocytes causing them to secrete helper factors faster and to a greater extent than normally occurs in aging mice. Characterization of the poly A:U induced helper factors is planned following their concentration of isolation. Their cellular target of action and their capability at modulating surface membrane receptors will be assessed.